Clamping device for clamping a printing plate upon a cylinder of a printing press

ABSTRACT

A device for clamping a printing plate to a cylinder such as the form cylinder of a printing press or similar machine permits convenient and rapid pivotal mounting of the clamping jaw to the tensioning bar of the device and an equally convenient and rapid release therefrom. For this purpose, the jaw and the tensioning bar are hinged to each other by a plurality of lengthwise spaced bearing elements and these elements engage each other in one axial position of the jaw and the bar relative to each other while in another axial position the bearing elements on the jaw face the spaces between the bearing elements on the bar whereby the jaw can be released from the bar by lifting it in radial direction. Mounting of the clamping jaw on the bar is effected by reversing the described relative displacement of the jaw and the bar.

United States, Patent Preuss 1151 3,658,002 1 51 Apr. 25, 1972 [541CLAMPING DEVICE FOR CLAMPING A PRINTING PLATE UPON A CYLINDER OF APRINTING PRESS Friedrich Preuss, Neu-lsenburg, Germany RolandOifsetmaschinenfabrik Faber & Schleicher AG, Offenbach am Main, Germany7 Apr. 15, 1970 [72] inventor:

[73] Assignee:

Filed:

Appl. No.:

[30] Foreign Application Priority Data May 3, 1969 Germany ..P 19 22749.7

U.S.Cl ..10l/415.l, 101/378 Int. Cl. ..B4lf 27/06, B4 lf27/ i 2FieldofSearch ..l0l/4l5.l, 378; 16/171, 172,

[56] References Cited UNITED STATES PATENTS 3/1966 Daley ..l6/l7l 5/1942Stahl..... il/l964 Shank ..101/41S.l

2,775,198 12/1956 Johnson et al..v ..lOl/415.i 3,119,331 1/1964 Koch etal... ..l0l/4l5.l 2,767,653 10/1956 Babicz ..101/4l5.l X

. FORElGN PATENTS OR APPLiCATlONS 1,291,750 7/1967 Germany.. ..1o1/41s.1

Primary Examiner-Robert E. Pulfrey Assistant Examiner-E. M. CovenAttorney-Ham, Baxley & Spiecens [5 7] ABSTRACT A device for clamping aprinting plate to a cylinder such as the form cylinder of a printingpress or similar machine permits convenient and rapid pivotal mountingof the clamping jaw to the tensioning bar of the device and an equallyconvenient and rapid release therefrom. For this purpose, the jaw andthe tensioning bar are hinged to each other by a plurality of lengthwisespaced bearing elements and these elements engage each other in oneaxial position of the jaw and the bar relative to each other whileinjanother axial position the bearing elements on the jaw face thespaces between the bearing elements on the bar whereby the jaw can bereleased from the bar by lifting it in radial direction. Mounting of theclamping jaw on the bar is effected by reversing the described relativedisplacement of the jaw and the bar.

6 Claims, 7 Drawing Figures BACKGROUND Printing press cylinders of thekind here involved generally have lengthwise peripheral grooves. Thereare known clamp ing devices of the general kind above referred to inwhich a tensioning bar is mounted in each of these grooves lengthwisetherein and a clamping jaw hinged to the tensioning bar can be pivotedby an eccentric means into and out of a position.

clamping the respective plate end against the tensioning bar. Aftereffective clamping of the plate ends the tensioning bars are displacedin circumferential direction to effect the required tensioning of theplate.

As is evident, the general purpose of a clamping device of this kind isto secure the printing plate upon predetermined areas of the peripheralwall of the cylinder. Clamping devices of this kind, to be satisfactory,should require a minimum of space to retain a maximal peripheral areafor the printing plate to be clamped. It is also required that thedevice is readily accessible and can be conveniently serviced, asobviously the device being mounted on the cylinder is bound to come incontact with ink, moisture and cleaning fluids.

U.S. Pat. No. 3,156,184 discloses a clamping device of the general kindabove referred to in which the pivotal connection between the tensioningbar and the clamping jaw is effected by a plurality of ball jointsmounted along the tensioning bar. The heads of screws screwed into thetensioning bars are spherically formed and thus serve as the balls ofthe joints. The clamping jaw and the tensioning bar can be detached fromeach other only when and after all these screws are removed from thetensioning bar. Such an operation is obviously cumbersome andtime-consuming. A further reason why the described hinging of theclamping jaw to the tensioning bar is not economically acceptable isthat the screws when inserted must be carefully adjusted so that theball heads thereof are all at the same level, as otherwise the jointscould not function smoothly.

French Pat. No. 1,044,012 shows a clamping device in which the printingplate to be mounted has reinforced ends each formed with a notched orserrated profile which cooperates with a similarly shaped profile formedin a bar of the device. The profiled ends of the plate and the bar canbe joined to or separated from each other by lengthwise displacing thebar. There are no provisions for a pivotal connection between the barand the respective profiled plate end.

THE INVENTION It is an important object of the invention to provide anovel and improved clamping device which permits rapid and con venientclamping of a printing plate to a cylinder or other mounting surface anda similarly rapid and convenient release of the plate from the cylinder.

Another important object of the invention is to provide a novel andimproved clamping device of the general kind above referred to in whichthe clamping jaw can be rapidly and easily pivotally connected to thetensioning bar of the device and equally easily and rapidly removed fromthe tensioning bar.

Another important object of the invention is to provide a novel andimproved clamping device of the general kind above referred to in whichcoupling and separation, respectively, of the clamping jaw and thetensioning bar of the device are effected by simply axially displacingthe clamping jaw and the tensioning bar relative to each other.

SUMMARY OF THE INVENTION The aforepointed out objects, features andadvantages, and other objects, features and advantages which will bepointed out hereinafter are obtained by mounting in an axially elongategroove of a printing press cylinder a clamping device including atensioning bar which is adjustably retained in its axial position in thegroove and is also displaceable in circumferential direction. Theclamping jaw of the device is pivotally connectable to the tensioningbar by hinge means which include a plurality of axially spaced bearingelements on the tensioning bar and a corresponding plurality of axiallyspaced bearing elements on the clamping jaw. These bearing elements arein pivotal engagement with each other in one axial position of theclamping jaw with reference to the tensioning bar and clear of eachother in another axial position of the clamping jaw with reference tothe tensioning bar. In the latter position the clamping jaw can besimply lifted out of the tensioning bar.

The spaces between adjacent bearing elements on the tensioning barmember are axially wider than the axial length of the bearing elementson the clamping jaw so that the clamping jaw and the tensioning bar canbe easily separated by placing the bearing elements on the jaw inregistry with the spaces between the bearing elements on the bar andthen lifting the jaw out of the bar. Joining of the jaw and the bar iseffected by placing the jaw and the bar into an axial position relativeto each other in which the bearing elements are in registry.

The structure of the clamping device according to the invention reducesto a minimum the space requirement thereof in circumferential direction;in other words, the device presents an optimal solution of the problem.Moreover, the device permits convenient access-and without requiring theuse of a tool-to parts of the device which are covered by the clampingjaw in devices of the type as heretofore known. Access is, for instance,necessary to the usual roughened or profiled surfaces of the devicebetween which the ends of the printing plate are actually clamped.Moreover, it is easily possible to select a clamping jaw which isspecifically designed for the type of printing plate to be used, such asa plate made of zinc or a metal alloy. As is evident, exchange of theclamping jaws is very convenient with the clamping device of theinvention.

DETAILED DESCRIPTION OF THE INVENTION In the accompanying drawing, apreferred embodiment of the invention is shown by way of illustrationand not by way of limitation.

In the drawing:

FIG. I is a sectional elevational view of a clamping device according tothe invention taken on line H of FIG. 2;

FIG. 2 is a plan view of FIG. 1 on a reduced scale;

FIG. 3 is a side view of FIG. 2;

FIG. 4 is a detailed view of the clamping jaw of the device, 5

of a printing plate 5. As a matter of convenience, there is shown onlythe clamping device for one plate end, but it should be understood thatthe other plate end is clamped in the same manner.

The clamping device comprises a tensioning bar 6 which extendslengthwise in the groove and is displaceable transverse of its length,that is, in the circumferential direction of the peripheral wall of thecylinder by turning a screw 7 against the action of a spring 8 (see FIG.2). The bar is guided by a guide track 9 (see FIG. 3), which is fixedlysecured to the body of the cylinder and extends approximately incircumferential direction. Guide 9 is engageable with a notch 10 in bar6. The position of the bar in the direction of the cylinder axis isadjustable by a set screw 11 threadable into the bar at the respectiveend thereof. The set screw abuts against the body of the cylinder.

Tension bar 6 has a lengthwise extending and upwardly protruding rib 12(see FIGS. 5 and 7) along which several spaced apart generallyhook-shaped protrusions 13 are provided. A clamping jaw 14 of the devicealso has a lengthwise rib 15 along which several generally hook-shapedprotrusions 16 are formed, as best shown in FIGS. 4 and 6.

Protrusions 13 on bar 6 and protrusions 16 on jaw 14 constitutepivotally engageable bearing elements which are held in engagement bythe action of a loaded spring 17 (see FIG. 1) abutting against tensionbar 6. The spring is guided in a bore 18 of bar 6 and acts upon jaw 14by means of a strip 19 fixedly secured to the jaw.

As is clearly shown in FIGS. 4 and 5, the engageable surfaces of bearingelements 13 and 14 have a generally circular curvature so that clampingjaw 14 can pivot about an axis 20 and can also be displaced lengthwiseof this axis. Accordingly, jaw 14 constitutes in effect a two-armedlever, the fulcrum of which is at axis 20. The two arms of this leverare designated by 21 and 26.

A rod 23 of eccentric cross section is interposed between lever arm 21and tension bar 6 and a support strip 22 steadies the rod in position,as shown in FIG. 1. Rod 23 can be rotated about its axis by means ofscrews 24 at the end of the rod, as is best shown in FIG. 2. Rotation ofthe rod effects rotation of clamping jaw 14 about its fulcrum 20 againstthe action of spring 17. Rod 23 may be steadied in position by holders25, suitably secured, for instance by screws, to tension bar 6.

As best shown in FIG. 1, the end 4 of printing plate 5 is clampedbetween lever arm 26 of jaw 14 and a member 27 when jaw 14 is pivoted,as just described. Member 27 may constitute a portion of tension bar 6.As shown, a rod 28 of for instance rectangular cross section isinterposed between member or bar portion 27 and the main body of tensionbar 6. This rod engages with two opposite corners generally triangularnotches or grooves 29 and 30 formed in member 27 and tension bar 6,respectively and so shaped that the bar will slightly tilt about itscorners in response to a tensioning pull applied to plate end 4, thatis, a pull toward the left as shown in FIG. 1. As a result of suchtilting, the effective cross-sectional width of rod 28 is slightlyincreased, thereby correspondingly increasing the clamping force withwhich plate end 4 is held between jaw part 26 and bar portion 27. Asshown in FIG. 1, a leaf spring 31 abuts against member 27 and biases rod28 into the angular position in which it does not produce theaforedescribed additional clamping force.

, The convenience with which the clamping jaw 14 can be as- :membled ona device according to the invention and disassembled therefrom can bestbe apprehended by an inspection of FIGS. 6 and 7. In these figuresclamping jaw 14 is shown in a position with reference to the position ofthe tension bar 6 such that bearing elements 16 are in alignment withthe gaps 13a between bearing elements 13. These figures also show thatthe spaces between bearing elements 13 are axially wider than the axialwidths of bearing elements 16 so that it is not necessary to place thebearing element 16 in perfectly centered alignment with spaces 13a.

To join the clamping jaw 14 to the tensioning bar 6, it is merelynecessary to push bearing element 16 into the spaces between elements 13and then to displace the clamping jaw relative to the tensioning baruntil bearing elements 13 and 16 are in engagement with each other.Disassembly of the clamping jaw is effected by reversing theaforedesciibed steps.

Tension bar 6 is formed with a recess 32 to accommodate strip 19. Thisstrip is so dimensioned and shaped that it is in contact with spring 17when and while the clamping jaw is inserted into tension bar 6 and alsowhen the jaw is axially displaced relative to bar 6. Accordingly, therespective end portion of strip 19 is always overlying bore 18 so thatthe loaded spring therein cannot jump out of the bore.

As previously indicated, FIGS. 2, 3, 6 and 7 show only one end of theclampingdevice, the other endthereof being constructed correspondingly.

While the invention has been described in detail with respect to acertain now preferred example and embodiment of the invention, it willbe understood by those skilled in the art, after understanding theinvention, that various changes and modifications may be made withoutdeparting from the spirit and scope of the invention, and it isintended, therefore, to cover all such changes and modifications in theappended claims.

What is claimed is:

l. A clamping device for clamping a printing plate upon a printing presscylinder having an axially elongate groove in its peripheral wall, saidclamping device comprising in combination:

an elongate tensioning member;

mounting means for mounting said tensioning member lengthwise within thegroove of the cylinder so as to permit displacement of said member incircumferential direction in said groove;

an elongate axially displaceable clamping jaw member;

hinge means supporting said jaw member on the tensioning member paralleltherewith for selectively pivoting said jaw member into and out of apivotal position in which a printing plate end is clamped between saidmembers,

said hinge means including a plurality of axially spaced bearingelements supported by the tensioning member and a correspondingplurality of axially spaced bearing elements supported on the jawmember, a first axial displacement of the jaw member moving the bearingelements on said member into registry with the spaces between thebearing elements on the tensioning member, a subsequent circumferentialdisplacement of the tensioning member, with the bearing elements on thejaw member in said position of registry, moving the bearing elements onthe tensioning member into lengthwise alignment with the bearingelements on the jaw member and a second axial displacement of the jawmember moving the bearing elements on said member into hingingrelationship with the bearing elements on the tensioning member.

2. The device according to claim 1 wherein said bearing elements are inthe form of engageable hooks.

3. The device according to claim 1 wherein the spaces between adjacentbearing elements on one of said members are axially wider than the axiallength of the bearing elements on the other of said members tofacilitate placement of the bearing elements on one member in registrywith the spaces on the other member.

4. The device according to claim 3 wherein said axially wider spaces areprovided at the tensioning member.

5. The device according to claim 1 and comprising actuating means forselectively pivoting the jaw member into either one of said pivotalpositions, said actuating means including an elongate eccentric memberinterposed between the tensioning member and the jaw member, saideccentric member being rotatable about its axis and in engagement withsaid members whereby rotation of said eccentric member pivots the jawmember into and out of its clamping position respectively and retainsthe jaw member in the selected one of said positions.

6. The device according to claim 1 wherein said tensioning membercomprises a yielding axially elongate portion engageable with theprinting plate and to be clamped and disposed juxtaposed to the clampingjaw member, and wherein a bar of .polygonal cross section is interposedin a gap between said yielding portion and a rigid portion of thetensioning member, said bar in response to a circumferentialdisplacement of the tensioning member being tilted about its axis intoan angular position in which the effective cross section width of thebar with respect to said gap is increased, thereby pressing saidyielding portion of the tensioning member toward said jaw member.

1. A clamping device for clamping a printing plate upon a printing presscylinder having an axially elongate groove in its peripheral wall, saidclamping device comprising in combination: an elongate tensioningmember; mounting means for mounting said tensioning member lengthwisewithin the groove of the cylinder so as to permit displacement of saidmember in circumferential direction in said groove; an elongate axiallydisplaceable clamping jaw member; hinge means supporting said jaw memberon the tensioning member parallel therewith for selectively pivotingsaid jaw member into and out of a pivotal position in which a printingplate end is clamped between said members, said hinge means including aplurality of axially spaced bearing elements supported by the tensioningmember and a corresponding plurality of axially spaced bearing elementssupported on the jaw member, a first axial displacement of the jawmember moving the bearing elements on said member into registry with thespaces between the bearing elements on the tensioning member, asubsequent circumferential displacement of the tensioning member, withthe bearing elements on the jaw member in said position of registry,moving the bearing elements on the tensioning member into lengthwisealignment with the bearing elements on the jaw member and a second axialdisplacement of the jaw member moving the bearing elements on saidmember into hinging relationship with the bearing elements on thetensioning member.
 2. The device according to claim 1 wherein saidbearing elements are in the form of engageable hooks.
 3. The deviceaccording to claim 1 wherein the spaces between adjacent bearingelements on one of said members are axially wider than the axial lengthof the bearing eleMents on the other of said members to facilitateplacement of the bearing elements on one member in registry with thespaces on the other member.
 4. The device according to claim 3 whereinsaid axially wider spaces are provided at the tensioning member.
 5. Thedevice according to claim 1 and comprising actuating means forselectively pivoting the jaw member into either one of said pivotalpositions, said actuating means including an elongate eccentric memberinterposed between the tensioning member and the jaw member, saideccentric member being rotatable about its axis and in engagement withsaid members whereby rotation of said eccentric member pivots the jawmember into and out of its clamping position respectively and retainsthe jaw member in the selected one of said positions.
 6. The deviceaccording to claim 1 wherein said tensioning member comprises a yieldingaxially elongate portion engageable with the printing plate and to beclamped and disposed juxtaposed to the clamping jaw member, and whereina bar of polygonal cross section is interposed in a gap between saidyielding portion and a rigid portion of the tensioning member, said barin response to a circumferential displacement of the tensioning memberbeing tilted about its axis into an angular position in which theeffective cross section width of the bar with respect to said gap isincreased, thereby pressing said yielding portion of the tensioningmember toward said jaw member.